House of Eyes

When Darren Hatman reports his daughter Leanne missing, DI Wesley Peterson isn't too concerned. Leanne works at Eyecliffe Castle, now converted into a luxury hotel. When Darren is found murdered in the grounds, Wesley suspects a connection between the recent crimes, the disappearance of two girls in the 1950s and a mysterious Sicilian ruin called the House of Eyes.  Book 20 of series.